Non-consecutive Nights Research Articles

Associations of nocturnal sleep with experimental pain and pain catastrophizing in healthy volunteers

Strong alterations of night sleep (e.g., sleep deprivation, insomnia) have appeared to affect pain in inducing hyperalgesic changes. However, it has remained unclear whether everyday variations of night sleep in healthy individuals have any influence on pain processing. Forty healthy subjects were studied by portable polysomnography (PSG) and sleep questionnaire during two non-consecutive nights at home. Experimental pain parameters (pressure pain threshold, temporal summation = TS, conditioned pain modulation = CPM) and situational pain catastrophizing (Situational Catastrophizing Questionnaire = SCQ) were always assessed the evening before and the morning after sleep recording in a pain laboratory. Linear regression analyses were computed to test the prediction of overnight changes in pain by different sleep parameters. Significant prediction of changes in pain parameters by sleep parameters was limited (2 out of 12 analyses), indicating that everyday variations in sleep under non-pathological and low stress conditions are only weakly associated with pain.

Effects of subthalamic nucleus deep brain stimulation on objective sleep outcomes in Parkinson's disease.

Sleep dysfunction is a common and disabling non-motor symptom in Parkinson's disease. Deep brain stimulation (DBS) of the subthalamic nucleus (STN) improves motor symptoms and subjective sleep in PD, but alternative stimulation parameters to optimize sleep have not been explored. We hypothesized that low frequency STN DBS would improve objective sleep more than conventional settings. Twenty PD subjects with STN DBS (18 unilateral, 2 bilateral) underwent 3 non-consecutive nights of polysomnography: DBS off; DBS high frequency (≥130 Hz); and DBS low frequency (60 Hz). Motor symptom tolerability was assessed 30 minutes after resumption of baseline settings the morning following polysomnography. The primary outcome was change in sleep efficiency between high and low frequency nights measured with repeated measures ANOVA. There was no difference in sleep efficiency between nights at high frequency (82.1% (72.6-90.1)) (median (IQR)), low frequency (81.2% (56.2-88.8)), or DBS off (82.8% (75.7-87.4)), p=0.241. Additionally, there was no difference in sleep stage percent, arousals, limb movements, subjective sleep quality, or objective vigilance measures. These outcomes did not change after adjusting for age, sex, disease duration, or side of surgery. No residual adverse motor effects were noted. Although well tolerated, low frequency STN DBS did not improve objective sleep in PD. Remarkably, objective measures of sleep were not worse with DBS off. These observations point to the potential for adaptive stimulation approaches, through which DBS settings could be optimized during sleep to meet individual needs. Additionally, these changes could preserve battery life without compromising patient outcomes.

A pilot study of serotonin-1A receptor genotypes and rapid eye movement sleep sensitivity to serotonergic/cholinergic imbalance in humans: a pharmacological model of depression.

RationaleThe serotonergic and cholinergic systems are jointly involved in regulating sleep but this system is theorized to be disturbed in depressed individuals. We previously reported that cholinergic and serotonergic agents induce sleep changes partially consistent with monoamine models of sleep disturbances in depression. One potential cause of disturbed neurotransmission is genetic predisposition. The G(-1019) allele of the serotonin-1A (5-HT1A) receptor promoter region predicts an increased risk for depression compared to the wild-type C(-1019) allele.ObjectiveThe goal of this study was to investigate how serotonin-1A receptor genotypes mediate sleep sensitivity to pharmacological probes modeling the serotonergic/cholinergic imbalance of depression.MethodsSeventeen healthy female participants homozygous for either C (n=11) or G (n=6) alleles aged 18–27 years were tested on four nonconsecutive nights. Participants were given galantamine (an anti-acetylcholinesterase), buspirone (a serotonergic agonist), both drugs together, or placebos before sleeping.ResultsAs reported previously, buspirone significantly increased rapid eye movement (REM) latency (P<0.001), as well as awakenings, percentage of time spent awake, and percentage of time asleep spent in stage N1 (P<0.019). Galantamine increased awakenings, percentage of time spent awake, percentage of time asleep spent in stage N1, and percentage of time asleep spent in REM, and decreased REM latency and percentage of time asleep spent in stage N3 (P<0.019). Galantamine plus buspirone given together disrupted sleep more than either drug alone, lowering sleep efficiency and percentage of time asleep spent in stage N3 and increasing awakenings, percentage of time spent awake, and percentage of time asleep spent in stage N1 (P<0.019). There was no main effect of genotype nor was there a significant multivariate interaction between genotype and drug condition.ConclusionThese findings are partially consistent with the literature about sleep in depression, notably short REM latency, higher percentage of total sleep time spent in REM, lower percentage of time asleep spent in stage N3, and increased sleep fragmentation. The C/G mutation in the serotonin-1A receptor promoter region does not appear to cause noticeable differences in the sleep patterns of a relatively small sample of healthy young females. Future studies with larger sample sizes are required.

The effects of galantamine and buspirone on sleep structure: Implications for understanding sleep abnormalities in major depression.

The serotonergic and cholinergic systems are jointly involved in regulating sleep, but this balance is theorized to be disturbed in depressed individuals. The goal of this study was to use biological probes in healthy participants, to model the serotonergic/cholinergic imbalance of depression and its associated abnormalities in sleep structure. We tested 20 healthy female participants 18-30 years of age on four non-consecutive nights. Participants were given galantamine (a cholinergic agent), buspirone (a serotonergic agonist), both drugs together, or placebo before sleeping. Buspirone suppressed tonic rapid eye movement (REM): There was a significant increase in REM latency (p < 0.001). Galantamine increased tonic REM sleep, leading to more time spent in REM (p < 0.001) and shorter REM latency (p < 0.01). Galantamine and buspirone given together were not significantly different from the placebo night by REM sleep measures, but disrupted sleep more than either drug alone. These findings are partially consistent with the cholinergic literature about sleep in depression, notably short REM latency, higher percentage of total sleep time spent in REM and increased sleep fragmentation. The prolonged REM latency and reduced percentage of REM with buspirone resembled the effect of selective serotonin reuptake inhibitor antidepressants on REM sleep.

A rehabilitation unit at night: environmental characteristics of patient rooms

Purpose: The aim of this study was first of all to investigate the sound, light, temperature and humidity levels in a rehabilitation ward and to establish whether the measured levels were within the recommended levels or not; secondly to explore influence of the type of the patient rooms on obtained measurements. Methods: Measurements of environmental characteristics were recorded on three non-consecutive nights by data loggers in a 12-bedded residential neurological rehabilitation unit for patients with disorders of consciousness. The obtained measurements were compared with the recommendations of the World Health Organization and the Society of Light and Lighting. Results: Recordings were within recommended levels for light and humidity overnight. Average noise levels were above the recommended levels. There were abrupt increases of light and noise levels which were high enough to cause sleep fragmentation. Mean temperature levels were higher than recommended. Conclusions: Our results indicated that the patients are at risk of disturbed sleep for the duration of their stay in rehabilitation unit. Exposure to generally high noise levels, as well as the sudden increases of noise and light intensities can prevent reaching restful night-time sleep and may negatively impact on rehabilitation process due to impaired memory, learning and well-being.Implications for RehabilitationStandards for ward based hospital environments to minimize sleep disturbance exist and can be used to examine the environmental characteristics of patients’ rooms in different healthcare settings including rehabilitation units.This study shows that measurements of environmental factors were not always within the recommended levels in the rehabilitation unit and presence of abrupt increase of noise and light levels are likely to cause sleep disturbance of patients.Assessment of current practice, education and training of night staff to raise awareness on importance of sleep and environmental factors and development of strategies are required in order to improve quality of sleep in rehabilitation settings.

Time for actions in lucid dreams: effects of task modality, length, and complexity

The relationship between time in dreams and real time has intrigued scientists for centuries. The question if actions in dreams take the same time as in wakefulness can be tested by using lucid dreams where the dreamer is able to mark time intervals with prearranged eye movements that can be objectively identified in EOG recordings. Previous research showed an equivalence of time for counting in lucid dreams and in wakefulness (LaBerge, 1985; Erlacher and Schredl, 2004), but Erlacher and Schredl (2004) found that performing squats required about 40% more time in lucid dreams than in the waking state. To find out if the task modality, the task length, or the task complexity results in prolonged times in lucid dreams, an experiment with three different conditions was conducted. In the first condition, five proficient lucid dreamers spent one to three non-consecutive nights in the sleep laboratory. Participants counted to 10, 20, and 30 in wakefulness and in their lucid dreams. Lucidity and task intervals were time stamped with left-right-left-right eye movements. The same procedure was used for the second condition where eight lucid dreamers had to walk 10, 20, or 30 steps. In the third condition, eight lucid dreamers performed a gymnastics routine, which in the waking state lasted the same time as walking 10 steps. Again, we found that performing a motor task in a lucid dream requires more time than in wakefulness. Longer durations in the dream state were present for all three tasks, but significant differences were found only for the tasks with motor activity (walking and gymnastics). However, no difference was found for relative times (no disproportional time effects) and a more complex motor task did not result in more prolonged times. Longer durations in lucid dreams might be related to the lack of muscular feedback or slower neural processing during REM sleep. Future studies should explore factors that might be associated with prolonged durations.

Artificial Pancreas Using a Personalized Rule-Based Controller Achieves Overnight Normoglycemia in Patients with Type 1 Diabetes

This study assessed the efficacy of a closed-loop (CL) system consisting of a predictive rule-based algorithm (pRBA) on achieving nocturnal and postprandial normoglycemia in patients with type 1 diabetes mellitus (T1DM). The algorithm is personalized for each patient's data using two different strategies to control nocturnal and postprandial periods. We performed a randomized crossover clinical study in which 10 T1DM patients treated with continuous subcutaneous insulin infusion (CSII) spent two nonconsecutive nights in the research facility: one with their usual CSII pattern (open-loop [OL]) and one controlled by the pRBA (CL). The CL period lasted from 10 p.m. to 10 a.m., including overnight control, and control of breakfast. Venous samples for blood glucose (BG) measurement were collected every 20 min. Time spent in normoglycemia (BG, 3.9-8.0 mmol/L) during the nocturnal period (12 a.m.-8 a.m.), expressed as median (interquartile range), increased from 66.6% (8.3-75%) with OL to 95.8% (73-100%) using the CL algorithm (P<0.05). Median time in hypoglycemia (BG, <3.9 mmol/L) was reduced from 4.2% (0-21%) in the OL night to 0.0% (0.0-0.0%) in the CL night (P<0.05). Nine hypoglycemic events (<3.9 mmol/L) were recorded with OL compared with one using CL. The postprandial glycemic excursion was not lower when the CL system was used in comparison with conventional preprandial bolus: time in target (3.9-10.0 mmol/L) 58.3% (29.1-87.5%) versus 50.0% (50-100%). A highly precise personalized pRBA obtains nocturnal normoglycemia, without significant hypoglycemia, in T1DM patients. There appears to be no clear benefit of CL over prandial bolus on the postprandial glycemia.

Does training increase NREM dream recall? A pilot study

The percentages of successful dream recall vary depending on whether the participants were awakened from REM sleep (about 80% recall) or NREM sleep (about 50% recall). The question as to whether this difference is explained by less dreaming during NREM sleep or sleep state-dependent memory processes cannot answered easily. The present pilot study was designed to test whether high recallers can increase their NREM dream recall to figures equal to those obtained from REM awakenings. The participants were awakened during NREM on three non-consecutive nights while training in dream recall by keeping a dream diary. Even though the study’s goal was not achieved, the findings support the hypothesis that dreaming is always present during NREM sleep and that reduced NREM recall percentages are explained by sleep stage-dependent recall processes. Future research should focus on these sleep stage-dependent recall processes and correlate possible interindividual differences with their differences in dream recall.

Collection of Culicoides spp. with four light trap models during different seasons in the Balearic Islands

Bluetongue (BT) is a viral disease that affects ruminants, being especially pathogenic in certain breeds of sheep. Its viral agent (bluetongue virus; BTV) is transmitted by several species of Culicoides biting midges (Diptera: Ceratopogonidae). Different models of suction light traps are being used in a number of countries for the collection of BTV vector species. To determine the relative effectiveness of different light traps under field conditions, four traps (Onderstepoort, Mini-CDC, Rieb and Pirbright) were compared. These traps were rotated between four sites on a cattle farm in Mallorca (Balearic Islands, Spain) for several non-consecutive nights. Results showed remarkable disparities in the efficacy of the traps for the collection of Culicoides midges. The highest number of midges collected in the Onderstepoort trap (x¯±SD=62±94.2) was not significantly different from that collected in the Mini-CDC (x¯±SD=58±139.2). The Rieb trap collected the lowest number of midges (x¯±SD=3±4.0). Significantly higher mean numbers of midges were collected in the Onderstepoort than in either the Pirbright (P=0.002) or Rieb traps (P=0.008). There were also differences in the Culicoides species composition as determine with the various traps. These results indicate that the Onderstepoort or Mini-CDC traps will be more effective than either the Rieb or Pirbright traps for the collection of large numbers of Culicoides midges.

A Novel Nasal Expiratory Positive Airway Pressure (EPAP) Device for the Treatment of Obstructive Sleep Apnea: A Randomized Controlled Trial

Investigate the efficacy of a novel nasal expiratory positive airway pressure (EPAP) device as a treatment for obstructive sleep apnea (OSA). A prospective, multicenter, sham-controlled, parallel-group, randomized, double-blind clinical trial. 19 sites including both academic and private sleep disorder centers Obstructive sleep apnea with a pre-study AHI ≥10/hour Treatment with a nasal EPAP device (N=127) or similar appearing sham device (N=123) for 3 months. Polysomnography (PSG) was performed on 2 non-consecutive nights (random order: device-on, device-off) at week 1 and after 3 months of treatment. Analysis of an intention to treat group (ITT) (patients completing week 1 PSGs) (EPAP N=119, sham N=110) was performed. At week 1, the median AHI value (device-on versus device-off) was significantly lower with EPAP (5.0 versus 13.8 events/h, P<0.0001) but not sham (11.6 versus 11.1 events/h, P=NS); the decrease in the AHI (median) was greater (-52.7% vs. -7.3%, P<0.0001) for the ITT group. At month 3, the percentage decrease in the AHI was 42.7% (EPAP) and 10.1% (sham), P<0.0001. Over 3 months of EPAP treatment the Epworth Sleepiness Scale decreased (9.9 ± 4.7 to 7.2 ± 4.2, P<0.0001), and the median percentage of reported nights used (entire night) was 88.2%. The nasal EPAP device significantly reduced the AHI and improved subjective daytime sleepiness compared to the sham treatment in patients with mild to severe OSA with excellent adherence. ClinicalTrials.gov. Trial name: Randomized Study of Provent Versus Sham Device to Treat Obstructive Sleep Apnea (AERO). URL: http://www.clinicaltrials.gov/ct2/show/NCT00772044?term=Ventus&rank=1. NCT00772044.

Deux années de comparaison de pièges à &lt;em&gt;Culicoides&lt;/em&gt; dans les îles Baléares

Several types of light traps are being used in different European countries to help determine the potential vector species of blue­tongue virus (BTV). The four traps compared in this study were: i) the Onderstepoort trap – black light trap, with 8 W ultraviolet light tube used in the United Kingdom and Italy; ii) mini-CDC – black light, model 912, with 4 W UV light tube, used in Spain and Portugal; iii) Rieb trap, white light model, with 4 W UV light tube, used from 2000 to 2006 in France; iv) UK trap, with 4 W standard white incandescent bulb, used in the past in the UK and other European countries for African horse sickness surveillance. All traps included a downdraught suction fan. Tests were conducted from 18 Oct. to 19 Nov. 2007, from 18 Feb. to 4 June 2008, and from 1 Oct. to 28 Nov. 2008. During at least nine non-consecutive nights the traps were placed following a randomized block design in four different positions on a cattle farm located on the island of Mallorca (Balearic Islands, Spain). In 2008, only three traps (Onderstepoort, UK and mini-CDC) were tested. Results showed major differences in collecting Culicoides. The Onderstepoort trap showed the best performance in terms of total number of Culicoides captured in autumn both in 2007 and 2008. The UK trap, and especially the Rieb trap showed the lowest efficacy in terms of captures. In autumn 2008, the Onderstepoort trap cap­tured on average 90 Culicoides per night, whereas the mini-CDC captured on average 27. During spring 2008, however, the mini- CDC performed better as it captured on average 180 Culicoides per night, against 84 captured by the Onderstepoort. However, Fisher’s least significant difference test showed no statistically sig­nificant differences between the traps (P &lt; 0.05). No remarkable difference was observed between the four traps as they all cap­tured a similar range of species. Captures of Culicoides newsteadi were greater during the autumn, and those of C. obsoletus in the spring. Finally, the Onderstepoort trap showed a higher sensitiv­ity in catching Culicoides midges in low population levels of the vector, especially during the winter season.

Prevention of melatonin suppression by nocturnal lighting: relevance to cancer

The decreased melatonin production in humans and animals caused by environmental lighting, especially short wavelength lighting (between 470 and 525 nm) has been shown to be associated with an increased risk of cancer. The purpose of this study was to investigate whether blocking light in this wavelength range under bright light may prevent the suppression of melatonin, which could help to prevent cancer. Optical filter lenses were designed, allowing selective exclusion of all wavelengths below 530 nm. Salivary melatonin levels were measured under dim light (<5 lux), bright light (800 lux) and filtered light (800 lux) at hourly intervals between 2000 and 0800 h in 11 healthy young male participants (mean age 23.5+/-1.5 years). The measurements were taken during three nonconsecutive nights over a 2-week period. The Dim Light Melatonin Onset test was used as a marker of circadian phase. Nine of the 11 participants demonstrated preserved melatonin levels in filtered light similar to their dim light secretion profile. With filtered light, the participants had a mean relative amount of melatonin of 91.2 (P>0.05 between dim light and experimental condition). Unfiltered bright light drastically suppressed melatonin production with a mean relative amount of melatonin of 25.4 (P<0.05 between dim light and experimental condition). Preventing melatonin deficiencies using lenses that block light of low wavelength from reaching the retina presents a cost-effective, practical solution to the problem of increased malignancy rates in shift workers.

Reliability of Sleep EEG Measures: A Comment on Van Dongen et al

WE OFFER A SOMEWHAT BELATED COMMENT ON VAN DONGEN ET AL'S1 SURVEY ON THE RELIABILITY OF SLEEP ELECTROENCEPHALOGRAM (EEG) MEASURES. In their paper, Van Dongen and coworkers reviewed the research implications of high within-subject stability (i.e., inter-night reliability) of sleep measures, including EEG measured by computer. They pointed out important research issues on which this evidence bears. However, their extensive review omitted 2 substantial studies specifically focused on the reliability of computer-measured sleep EEG frequencies. In the first, Tan et al2 reported remarkably high inter-night reliability of delta, sigma, and beta frequencies during non-rapid eye movement sleep, measured with both fast Fourier transform and period-amplitude analysis. Subjects were 10 males and 6 females (mean age = 20 years) who underwent 5 consecutive nights of baseline recording. Internight reliability coefficients in these frequency bands were approximately 0.9 for fast Fourier transform power and period-amplitude measures of wave amplitude and incidence. For all measures, the mean of nights 1 and 2 correlated at approximately 0.95 with the 5-night mean. Tan et al noted that differences in skull impedance and other extra-cerebral factors could produce consistent individual differences in EEG amplitude that might spuriously enhance internight reliability of amplitude-weighted EEG measures (fast Fourier transform power and related period-amplitude measures). However, they found equally high reliability for an amplitude-free measure (period-amplitude time in band), indicating that it is the brain electrical activity that is reliable. In agreement with Linkowski et al's3 earlier suggestion based on visually scored sleep EEG, Tan et al proposed that non-rapid eye movement delta and other sleep EEG frequencies are individual traits that are heavily genetically determined. In their second paper, Tan et al4 presented internight reliability data for sleep EEG in 19 young adults (mean age 22 years, 10 men) and 19 elderly normal adults (mean age 71 years, 8 men). This remains the most extensive study of this question. Subjects were studied for 4 nonconsecutive nights, a design that challenges internight reliability more strongly than does one using consecutive nights. Digitized EEG in both non-rapid eye movement and rapid eye movement sleep was analyzed in 26 frequency bands using the fast Fourier transform and period-amplitude modules of PASSPLUS (Delta Software). Separate non-rapid eye movement and rapid eye movement spectra for each computer measure were constructed. In both age groups, non-rapid eye movement and rapid eye movement spectral curves differed significantly. Both spectra were complex curves with highly significant linear, quadratic, and cubic components. Again, the EEG measures were highly consistent within subjects, so much so that the spectra for each measure were virtually superimposed when plotted for individual subjects. Tan et al again demonstrated high within-subject Pearson reliability coefficients (∼.8 – ∼.95) for each frequency band. In both age groups, mean values for each measure were also stable across these nonconsecutive nights. To our surprise, and contradicting a speculation by Van Dongen et al, EEG spectra in the elderly were at least as reliable as those in young adults. Tan et al proposed that “The high reliability of computer-measured sleep EEG traits found here obviously invites their genetic investigation.”4p1551 It is encouraging that Van Dongen and colleagues have recently undertaken such studies.5

Effects of a Moderate Evening Alcohol Dose. II: Performance

This second of a pair of papers investigates the effects of a moderate dose of alcohol and staying up late on driving simulation performance and simple visual reaction time (RT) at a known circadian phase in well-rested young adults. Twenty-nine adults (9 males), ages 21 to 25 years, spent 1 week on an at-home stabilization schedule of 8.5 to 9 hours, followed by 3 nonconsecutive nights in-lab: adaptation, placebo, and alcohol. Performance task practice occurred on 3 occasions before the study. Alcohol (vodka; 0.54 g/kg men; 0.49 g/kg women mixed with tonic) was consumed over 30 minutes ending 1 hour before normal bedtime; the same quantity of beverage was given on placebo. Driving simulation (with drive-only and dual-task drive and subtract components) and psychomotor vigilance task (PVT) testing occurred before and after alcohol/placebo ingestion. Breath alcohol concentration (BrAC) readings were taken before all test sessions. Saliva samples were taken approximately every 30 minutes to determine circadian phase. Driving simulation and PVT variables significantly deteriorated with increasing time awake. Driving simulator lane variability was worse with alcohol compared with placebo at 15.5 hours awake. No PVT variable showed an effect of alcohol. Driving simulation performance deteriorated with extended waking and with alcohol; driving was most impaired at the peak alcohol level. The PVT, less complex than the driving simulation, did not show effects of alcohol, a finding consistent with previous literature that disruptive effects of low alcohol concentrations increase with task complexity. Overall, simulated driving performance is significantly impaired late at night when even a moderate dose of alcohol is consumed.

P.8.a.048 Childhood physical and sexual abuse in 100 nonviolent suicide attempters in Budapest

Yang W, Dollear M, Muthukrishnan SR. One rare side effect of zolpidem—sleepwalking: a case report. Arch Phys Med Rehabil 2005;86:1265℃6.Zolpidem is an imidazopyridine agent indicated for the short-term treatment of insomnia. Sleepwalking is a rare side effect of zolpidem. A review of the literature produced only 2 cases. We report a case of a male rehabilitation inpatient in his mid fifties with a history of alcoholism and traumatic brain injury who had undergone a right hip hemiarthroplasty. He had no history of somnambulism or insomnia but walked in his sleep on 2 nonconsecutive nights after taking zolpidem. He had exhibited no such behavior before taking zolpidem, on the intervening night that was he was not given medication, and after the medication was discontinued. We conclude that zolpidem can cause sleepwalking, and patients who have suffered a brain injury may be more susceptible to this side effect. Here we describe the clinical presentation and review the relevant literature on zolpidem and sleepwalking.

Sleep latency testing as a time course measure of state arousal

The purpose of this study was to determine how long the effects of a brief period of physiological arousal persisted using repeated sleep latency testing and measurement of heart rate. Thirteen normal sleeping young adults spent two non-consecutive nights and the following days in the laboratory. On each day, subjects had five sleep latency measurements - at 09:00, 09:30, 10:00, 10:30, and 11:00 hours. The 09:00 test was a premanipulation baseline. Following this nap, subjects either walked for 5 min (on one day) or rested in bed for 10 min (on another day) prior to the 09:30 hours sleep latency test. Significant increases in sleep latency were found at 09:30, 10:00, and 11:00 hours following the single 5-min walk as compared with resting in bed (mean sleep latency after the walk was 11.7 min compared with 7.1 min for the resting condition). Heart rate was significantly higher throughout all of the postmanipulation naps following the walk. The elevated sleep latency is probably secondary to the changes in underlying physiological arousal as measured in this study by heart rate.

One Rare Side Effect of Zolpidem—Sleepwalking: A Case Report

Yang W, Dollear M, Muthukrishnan SR. One rare side effect of zolpidem—sleepwalking: a case report. Arch Phys Med Rehabil 2005;86:1265℃6. Zolpidem is an imidazopyridine agent indicated for the short-term treatment of insomnia. Sleepwalking is a rare side effect of zolpidem. A review of the literature produced only 2 cases. We report a case of a male rehabilitation inpatient in his mid fifties with a history of alcoholism and traumatic brain injury who had undergone a right hip hemiarthroplasty. He had no history of somnambulism or insomnia but walked in his sleep on 2 nonconsecutive nights after taking zolpidem. He had exhibited no such behavior before taking zolpidem, on the intervening night that was he was not given medication, and after the medication was discontinued. We conclude that zolpidem can cause sleepwalking, and patients who have suffered a brain injury may be more susceptible to this side effect. Here we describe the clinical presentation and review the relevant literature on zolpidem and sleepwalking.

Blocking Low-Wavelength Light Prevents Nocturnal Melatonin Suppression with No Adverse Effect on Performance during Simulated Shift Work

Decreases in melatonin production in human and animals are known to be caused by environmental lighting, especially short-wavelength lighting (between 470 and 525 nm). We investigated the novel hypothesis that the use of goggles with selective exclusion of all wavelengths less than 530 nm could prevent the suppression of melatonin in bright-light conditions during a simulated shift-work experiment. Salivary melatonin levels were measured under dim (<5 lux), bright (800 lux), and filtered (800 lux) light at hourly intervals between 2000 and 0800 h in 11 healthy young males and eight females (mean age, 24.7 +/- 4.6 yr). The measurements were performed during three nonconsecutive nights over a 2-wk period. Subjective sleepiness was measured by self-report scales, whereas objective performance was assessed with the Continuous Performance Test. All subjects demonstrated preserved melatonin levels in filtered light similar to their dim-light secretion profile. Unfiltered bright light drastically suppressed melatonin production. Normalization of endogenous melatonin production while wearing goggles did not impair measures of performance, subjective sleepiness, or alertness.

Self-Reported Versus Recorded Sleep Position: An Observational Study

Background: Patient reports of ‘usual’ and ‘recent’ sleep positions are used by allied health professionals to direct the management of waking and nocturnal musculoskeletal symptoms. However no published studies have determined if self reports of sleep position are valid, consistent or reliable. An observational study was conducted at the Centre for Sleep Research of the University of South Australia. Twelve subjects, four in each of the age groups 18 to 39 years, 40 to 59 years and 60 years and over, without any known sleep disorders or sleep-disturbing medical or emotional problems participated in the study. Subjects spent two non-consecutive nights in a sleep laboratory, where an infra-red light source allowed their sleep position during the night to be recorded on video. Prior to retiring, subjects recorded the position in which they believed they spent the most time during a ‘usual’ nights sleep. In the morning, they recorded the position in which they believed they spent the most time during the recorded nights sleep. Videos were viewed in order to count the number of position shifts per night and to calculate the total amount of time each subject spent lying prone, supine and on their side. Subjects’ pre- and post-sleep questionnaire responses were then compared to the video record to determine validity, the amount of time spent in each sleep position was compared across the two nights to determine consistency and pre-and post-sleep questionnaire responses were compared to determine reliability of self reported sleep position. High correlation was found when comparing subjects’ self report of their common sleep positions with the video record. The sensitivity of self reported ‘usual’ night side lying sleep position was 89% and ‘last’ night reports 95%. Sleep position was consistent across repeated nights’ sleep, and there was good reliability between subjects’ self report of ‘usual’ (92%) and ‘last night’ (83%) sleep positions. This study reports high validity, reliability and consistency in self reports of ‘usual’ and ‘recent’ sleep positions

Effects of humid heat exposure on sleep, thermoregulation, melatonin, and microclimate

Nine healthy young male volunteers were recruited to participate in a study involving three non-consecutive nights of polysomnographically and thermoregulatory measured sleep. Nightly urine samples were assayed for the melatonin metabolite 6-sulfatoxymelatonin (aMT6s). Experimental conditions were 26°C 50% RH (26/50) and 32°C 80% RH (32/80), where the subjects wore pyjamas with cotton blanket. Rectal temperature ( T re) did not decrease during nocturnal sleep at 32/80. The duration of wakefulness and stage 1 sleep increased significantly at 32/80 compared to 26/50. Stage 2 and 4 sleeps were significantly shorter at 32/80 than at 26/50. Although there was no significant difference in urinary aMT6s between 32/80 and 26/50( n=6), the melatonin metabolite secretion tended to be lower at 32/80 than at 26/50 in accordance with the decrease in sleep efficiency index. Heart rate and sweat rate were significantly higher at 32/80 than at 26/50. The acute decrease in melatonin secretion during nocturnal sleep may be related to reduce sleep efficiency through thermoregulatory mechanisms.